Page 307 - (DK) Ocean - The Definitive Visual Guide

BRYOZOANS 305

Bryozoans ATTACHED TO SEAWEED
Bryozoans, such as this hard
species encrusting a seaweed, often
THESE COLONIAL live in areas with strong currents.
DOMAIN Eucarya
ANIMALS live
KINGDOM Animalia
attached to the sea
PHYLUM Bryozoa
bed and although
SPECIES 6,085 numerous, they are
often overlooked.
The individuals making up the colony are
1
usually less than / 32 in (1 mm) long, but the
colonies may span over 3 ft (1 m). Bryozoans are also
called ectoprocts or sea mats, the latter name referring
to their tendency to encrust the surfaces of stones and
seaweeds. Other colonial forms of bryozoan include coral-
like growths, branched plantlike tufts, and fleshy lobes. Most
species are marine, but a few live in fresh water.

Anatomy Habitats
A bryozoan colony is made up of individuals called zooids, and may With their great variety of body form,
contain several or up to many millions. Each zooid is encased in a bryozoans can be found in almost any habitat
box-shaped body wall of calcium carbonate or a gelatinous or hornlike from the seashore to the deep ocean, and from
material, and a small hole links it to other zooids. Arctic waters to tropical coral reefs. Colonies
To feed, the animal pushes a circular or are most often found firmly attached to
horseshoe-shaped structure (a lophophore) submerged rocks, seagrasses, seaweeds, BRYOZOANS UNDER ATTACK
Sea slugs often make a meal
out of an opening. This is crowned by mangrove roots, and dead shells, but some
of encrusting bryozoans,
tentacles covered in tiny, beating hairs encrusting species even hitch a ride on the breaking into each zooid
that draw in planktonic food. In most shells of living crustaceans and mollusks. A few and eating the insides.
species, fertilized eggs are stored in unusual species do not need a surface for
specialized zooids that form a brood support and can live in the sand; these bryozoan colonies can move
chamber for developing larvae. slowly over or through the sand by coordinated rowing movements
of a long projection found on specialized zooids.
Bryozoan colonies originate from a single larva that settles on the seabed
MAT OF ZOOIDS
This encrusting species of bryozoan has and becomes a zooid. More zooids are added to the colony by budding,
rectangular zooids joined in a single layer. a process in which a new zooid grows out from the side of the body
The resulting mat spreads over seaweeds. wall. Most bryozoan larvae are short-lived and settle near the parent.

ORDER CTENOSTOMATIDA ORDER CHEILOSTOMATIDA
Gelatinous Bryozoan Hornwrack

Alcyonidium diaphanum Flustra foliacea
SIZE (HEIGHT) SIZE (HEIGHT)
Up to 12 in (30 cm) Up to 8 in (20 cm)
DEPTH DEPTH
0–656 ft (0–200 m) 0–330 ft (0–100 m)
HABITAT HABITAT
Rocks and shelly sand Stones, shells, rock
DISTRIBUTION Temperate waters of northeastern DISTRIBUTION Temperate and Arctic waters of
Atlantic northeastern Atlantic
This species is often mistaken for a
brown seaweed. The colony grows up
from a narrow base as thin, flat, fan-like
lobes. These usually form dense clumps
and cover the sea bed like a crop of
tiny brown lettuces. They litter the
strandline on many shores in dried ORDER CHEILOSTOMATIDA Pink lace bryozoan colonies feel hard
clumps and, by using a magnifying and brittle to the touch because the
glass, an observer can easily see the Pink Lace Bryozoan walls of the individual zooids are
individual, oblong colony members. reinforced with calcareous material.
Colonies of this bryozoan have a firm, Iodictyum phoeniceum The colony is shaped like curly-edged
rubbery consistency and grow as SIZE (WIDTH) potato chips with a lacework of small
irregular, lobed, or fingerlike growths Up to 8 in (20 cm) holes. The beautiful dark pink to purple
that attach to their substrate with a DEPTH color remains even after the colony is
small, encrusting base. This species 50–130 ft (15–40 m) dead and dried. This species prefers to
may cause an allergic dermatitis when HABITAT live in areas with some current, and its OCEAN LIFE
handled, and North Sea fishermen are Rocky reefs holes may help reduce the force of the
often affected when their trawl nets DISTRIBUTION Temperate and tropical waters around water against it. Similar species are
have gone through areas of dense Australia found on coral reefs throughout the
bryozoan undergrowth. Indo-Pacific region.